Vista - Could not load file ...

I'm almost embarrassed to ask this, but believe it or not, I've spent about
30 mins on it so far.

I have a WinForm that has lots of references to some class libraries I've
created. Well, my WinForm has a reference to classlibrary1, and
classlibrary1 has a reference to classlibrary2. classlibrary2 just has some
static functions for processing.

Anyway, when I run my WinForm, it loads up fine. However, when I click the
button to call into classlibrary1 which calls into classlibrary2, I get a
"could not load file or assembly classlibrary2". My folder structure is as
follows:

rootdir
rootdir\location of classlibrary1
rootdir\location of classlibrary2

If I move classlibrary2 to into the rootdir, I'm sure it will work fine, but
I don't want to do that. I'm sure this is something stupid that I'm
missing, and I'm feeling pretty dumb today.

Anybody? My kids kept me up last night. Thanks.